The present embodiment relates generally to compositions and methods of utilizing the compositions for sealing a subterranean zone penetrated by a well bore to restore lost circulation.
While drilling oil and gas wells, a drilling fluid is circulated through a drill bit in a well bore and then back to the earth surface, thereby removing cuttings from the well bore. The drilling fluid is then often reconditioned and reused. In the well bore, the drilling fluid maintains a predetermined hydrostatic pressure. However, when the drill bit encounters certain unfavorable subterranean zones, the hydrostatic pressure is compromised, resulting in what is commonly known as “lost circulation.” For example, lost circulation occurs when the drill bit encounters comparatively low pressure subterranean zones, such as vugs, fractures, and other thief zones. Similarly, encountering comparatively high pressure subterranean zones results in crossflows or underground blow-outs, and subsequently lost circulation.
Lost circulation requires remedial steps. Most remedial steps comprise introducing lost circulation materials (“LCMs”) into the well bore to seal the above-described low pressure subterranean zones or high pressure subterranean zones. LCMs include low-cost waste products from the food processing or chemical manufacturing industries, such as ground peanut shells, mica, cellophane, walnut shells, calcium carbonate, plant fibers, cottonseed hulls, ground rubber, and polymeric materials. LCMs can be classified according to their properties, for example, there are formation bridging LCMs and seepage loss LCMs. Often, more than one LCM type must be placed down hole, based on the required LCM properties.